This is a basic feature for most social networking sites, and as Wikidot has a partly social-networking focus, I believe it should have this feature as well.

The only way I can find out if someone has added me is to go to my contacts list and to open a collapsible block… and see the list of people with me as one of their contacts. It should be more connected… if I add someone as a contact, they should get a PM to let them know and suggest that they add me back.

Forcing contact lists to be pending approval i.e. I can not add someone to my contacts list until they approve it and agree to it — that would be a better option, but would probably be more work to implement than the option I suggested above (which just involves sending a PM with one or two links in it)